Information search has become an important activity of people's daily lives. A person may search the Internet for a variety of information including, for example, the latest news, places of interest, entertainment, etc. However, given the ever-growing volume of information in the Internet, people find it increasingly more difficult to locate the particular information they desire. Although new search technologies have continuously been proposed and developed, these new search technologies rely heavily on processing and storage abilities of search engines and sometimes fall short of providing a user with the desired information. Furthermore, whether the user can successfully obtain information that he/she desires still depends heavily on his/her search skills, such as ability to describe information he/she desires using a few keywords. Even though the search engine may suggest a plurality of keywords as the user types in a query, these suggested keywords may fail to anticipate a search intention of the user.
Additionally, advertisers compete and bid against one another for prominent placement in search result pages in response to a particular keyword. After placing their advertisements on the search result pages, the advertisers will passively wait for users to click on their advertisements and read relevant web pages related to their products. Since the users may sometimes need to read most, if not all, of content on the web pages in order to determine whether they are interested in the products, most of the users simply ignore these advertisements, leading to a generally poor performance of this kind of advertising strategies.